using System;
using System.Runtime.InteropServices;   /* Marshaling */
using System.Threading;
using System.Collections.Generic;       /* Use of List */
using System.IO;                        /* Use of path */
using GhostAPI;                         /* Use of Ghostscript API */

namespace GhostMono
{
    public enum GS_Task_t
    {
        PS_DISTILL,
        CREATE_XPS,
        SAVE_RESULT,
        GET_PAGE_COUNT,
        GENERIC,
        DISPLAY_DEV_THUMBS_NON_PDF,
        DISPLAY_DEV_THUMBS_PDF,
        DISPLAY_DEV_NON_PDF,
        DISPLAY_DEV_PDF,
    }
    public enum GS_Result_t
    {
        gsOK,
        gsFAILED,
        gsCANCELLED
    }
    public enum gsStatus
    {
        GS_READY,
        GS_BUSY,
        GS_ERROR
    };

    /* Parameters */
    public struct gsParamState_t
    {
        public String outputfile;
        public String inputfile;
        public GS_Task_t task;
        public GS_Result_t result;
        public int num_pages;
        public List<int> pages;
        public int firstpage;
        public int lastpage;
        public int currpage;
        public List<String> args;
        public int return_code;
        public double zoom;
    };

    public class gsThreadCallBack
    {
        private bool m_completed;
        private int m_progress;
        private gsParamState_t m_param;
        public bool Completed
        {
            get { return m_completed; }
        }
        public gsParamState_t Params
        {
            get { return m_param; }
        }
        public int Progress
        {
            get { return m_progress; }
        }
        public gsThreadCallBack(bool completed, int progress, gsParamState_t param)
        {
            m_completed = completed;
            m_progress = progress;
            m_param = param;
        }
    }

    class ghostsharp
    {
        public class GhostscriptException : Exception
        {
            public GhostscriptException(string message) : base(message)
            {
            }
        }

        /* Ghostscript display device callback delegates. */

        /* New device has been opened */
        /* This is the first event from this device. */
        public delegate int display_open_del(IntPtr handle, IntPtr device);

        /* Device is about to be closed. */
        /* Device will not be closed until this function returns. */
        public delegate int display_preclose_del(IntPtr handle, IntPtr device);

        /* Device has been closed. */
        /* This is the last event from this device. */
        public delegate int display_close_del(IntPtr handle, IntPtr device);

        /* Device is about to be resized. */
        /* Resize will only occur if this function returns 0. */
        /* raster is byte count of a row. */
        public delegate int display_presize_del(IntPtr handle, IntPtr device,
            int width, int height, int raster, uint format);

        /* Device has been resized. */
        /* New pointer to raster returned in pimage */
        public delegate int display_size_del(IntPtr handle, IntPtr device,
                            int width, int height, int raster, uint format,
                            IntPtr pimage);

        /* flushpage */
        public delegate int display_sync_del(IntPtr handle, IntPtr device);

        /* showpage */
        /* If you want to pause on showpage, then don't return immediately */
        public delegate int display_page_del(IntPtr handle, IntPtr device, int copies, int flush);


        /* Notify the caller whenever a portion of the raster is updated. */
        /* This can be used for cooperative multitasking or for
		 * progressive update of the display.
		 * This function pointer may be set to NULL if not required.
		 */
        public delegate int display_update_del(IntPtr handle, IntPtr device, int x, int y,
              int w, int h);

        /* Allocate memory for bitmap */
        /* This is provided in case you need to create memory in a special
		 * way, e.g. shared.  If this is NULL, the Ghostscript memory device
		 * allocates the bitmap. This will only called to allocate the
		 * image buffer. The first row will be placed at the address
		 * returned by display_memalloc.
		 */
        public delegate int display_memalloc_del(IntPtr handle, IntPtr device, ulong size);

        /* Free memory for bitmap */
        /* If this is NULL, the Ghostscript memory device will free the bitmap */
        public delegate int display_memfree_del(IntPtr handle, IntPtr device, IntPtr mem);

        private int display_size(IntPtr handle, IntPtr device,
                            int width, int height, int raster, uint format,
                            IntPtr pimage)
        {
            m_pagewidth = width;
            m_pageheight = height;
            m_pageraster = raster;
            m_pageptr = pimage;
            return 0;
        }

        private int display_page(IntPtr handle, IntPtr device, int copies, int flush)
        {
            m_params.currpage += 1;
            Gtk.Application.Invoke(delegate {
                gsPageRenderedMain(m_pagewidth, m_pageheight, m_pageraster, m_pageptr, m_params);
            });
            return 0;
        }

        private int display_open(IntPtr handle, IntPtr device)
        {
            return 0;
        }

        private int display_preclose(IntPtr handle, IntPtr device)
        {
            return 0;
        }

        private int display_close(IntPtr handle, IntPtr device)
        {
            return 0;
        }

        private int display_presize(IntPtr handle, IntPtr device,
            int width, int height, int raster, uint format)
        {
            return 0;
        }

        private int display_update(IntPtr handle, IntPtr device, int x, int y,
              int w, int h)
        {
            return 0;
        }

        private int display_memalloc(IntPtr handle, IntPtr device, ulong size)
        {
            return 0;
        }

        private int display_memfree(IntPtr handle, IntPtr device, IntPtr mem)
        {
            return 0;
        }
        private int display_sync(IntPtr handle, IntPtr device)
        {
            return 0;
        }

        /* Delegate for stdio */
        public delegate int gs_stdio_handler(IntPtr caller_handle, IntPtr buffer,
            int len);

        private int stdin_callback(IntPtr handle, IntPtr pointer, int count)
        {
            String output = Marshal.PtrToStringAnsi(pointer);
            return count;
        }

        private int stdout_callback(IntPtr handle, IntPtr pointer, int count)
        {
            String output = null;
            try
            {
                output = Marshal.PtrToStringAnsi(pointer);    
                Gtk.Application.Invoke(delegate {
                    gsIOUpdateMain(output, count);
                });
            }
            catch (Exception excep2)
            {
                var mess = excep2.Message;
            }

            return count;

        }

        private int stderr_callback(IntPtr handle, IntPtr pointer, int count)
        {
            String output = Marshal.PtrToStringAnsi(pointer);
            Gtk.Application.Invoke(delegate {
                gsIOUpdateMain(output, count);
            });

            return count;
        }

        IntPtr gsInstance;
        IntPtr dispInstance;
        Thread m_worker;
        bool m_worker_busy;
        gsParamState_t m_params;
        IntPtr m_pageptr;
        int m_pagewidth;
        int m_pageheight;
        int m_pageraster;

        display_callback_t m_display_callback;
        IntPtr ptr_display_struct;

        /* Callbacks to Main */
        internal delegate void gsDLLProblem(String mess);
        internal event gsDLLProblem gsDLLProblemMain;

        internal delegate void gsIOCallBackMain(String mess, int len);
        internal event gsIOCallBackMain gsIOUpdateMain;

        internal delegate void gsCallBackMain(gsThreadCallBack info);
        internal event gsCallBackMain gsUpdateMain;

        internal delegate void gsCallBackPageRenderedMain(int width, int height, int raster,
            IntPtr data, gsParamState_t state);
        internal event gsCallBackPageRenderedMain gsPageRenderedMain;


        /* From my understanding you cannot pin delegates.  These need to be declared
		 * as members to keep a reference to the delegates and avoid their possible GC. 
		 * since the C# GC has no idea that GS has a reference to these items. */
        readonly gs_stdio_handler raise_stdin;
        readonly gs_stdio_handler raise_stdout;
        readonly gs_stdio_handler raise_stderr;

        /* Ghostscript display callback struct */
        public struct display_callback_t
        {
            public int sizeof_display_callback;
            public int major_vers;
            public int minor_vers;
            public display_open_del display_open;
            public display_preclose_del display_preclose;
            public display_close_del display_close;
            public display_presize_del display_presize;
            public display_size_del display_size;
            public display_sync_del display_sync;
            public display_page_del display_page;
            public display_update_del display_update;
            public display_memalloc_del display_memalloc;
            public display_memfree_del display_memfree;
        };
        public ghostsharp()
        {
            m_worker = null;
            gsInstance = IntPtr.Zero;
            dispInstance = IntPtr.Zero;

            /* Avoiding delegate GC during the life of this object */
            raise_stdin = stdin_callback;
            raise_stdout = stdout_callback;
            raise_stderr = stderr_callback;

            m_display_callback.major_vers = 1;
            m_display_callback.minor_vers = 0;
            m_display_callback.display_open = display_open;
            m_display_callback.display_preclose = display_preclose;
            m_display_callback.display_close = display_close;
            m_display_callback.display_presize = display_presize;
            m_display_callback.display_size = display_size;
            m_display_callback.display_sync = display_sync;
            m_display_callback.display_page = display_page;
            m_display_callback.display_update = display_update;
            //m_display_callback.display_memalloc = display_memalloc;
            //m_display_callback.display_memfree = display_memfree;
            m_display_callback.display_memalloc = null;
            m_display_callback.display_memfree = null;

            /* The size the structure when marshalled to unmanaged code */
            m_display_callback.sizeof_display_callback = Marshal.SizeOf(typeof(display_callback_t));

            ptr_display_struct = Marshal.AllocHGlobal(m_display_callback.sizeof_display_callback);
            Marshal.StructureToPtr(m_display_callback, ptr_display_struct, false);
            m_worker_busy = false;
        }


        /* Callback upon worker all done */
        private void gsCompleted(gsParamState_t Params)
        {
            gsThreadCallBack info = new gsThreadCallBack(true, 100, Params);
            m_worker_busy = false;
            Gtk.Application.Invoke(delegate {
                gsUpdateMain(info);
            });
        }

        /* Callback as worker progresses in run string case */
        private void gsProgressChanged(gsParamState_t Params, int percent)
        {
            /* Callback with progress */
            gsThreadCallBack info = new gsThreadCallBack(false, percent, Params);
            Gtk.Application.Invoke(delegate {
                gsUpdateMain(info);
            });
        }

        /* Callback for problem */
        private void gsErrorReport(string message)
        {
            Gtk.Application.Invoke(delegate {
                gsDLLProblemMain(message);;
            });
            m_worker_busy = false;
        }

		private gsParamState_t gsFileSync(gsParamState_t in_params)
		{
			int num_params = in_params.args.Count;
			var argParam = new GCHandle[num_params];
			var argPtrs = new IntPtr[num_params];
			List<byte[]> CharacterArray = new List<byte[]>(num_params);
			GCHandle argPtrsStable = new GCHandle();
			int code = 0;
			bool cleanup = true;

			try
			{
				code = ghostapi.gsapi_new_instance(out gsInstance, IntPtr.Zero);
				if (code < 0)
				{
					throw new GhostscriptException("gsFileSync: gsapi_new_instance error");
				}
				code = ghostapi.gsapi_set_stdio(gsInstance, stdin_callback, stdout_callback, stderr_callback);
				if (code < 0)
				{
					throw new GhostscriptException("gsFileSync: gsapi_set_stdio error");
				}
				code = ghostapi.gsapi_set_arg_encoding(gsInstance, (int)gsEncoding.GS_ARG_ENCODING_UTF8);
				if (code < 0)
				{
					throw new GhostscriptException("gsFileSync: gsapi_set_arg_encoding error");
				}

				/* Now convert our Strings to char* and get pinned handles to these.
				 * This keeps the c# GC from moving stuff around on us */
				String fullcommand = "";
				for (int k = 0; k < num_params; k++)
				{
					CharacterArray.Add(System.Text.Encoding.UTF8.GetBytes((in_params.args[k]+"\0").ToCharArray()));
					argParam[k] = GCHandle.Alloc(CharacterArray[k], GCHandleType.Pinned);
					argPtrs[k] = argParam[k].AddrOfPinnedObject();
					fullcommand = fullcommand + " " + in_params.args[k];
				}

				/* Also stick the array of pointers into memory that will not be GCd */
				argPtrsStable = GCHandle.Alloc(argPtrs, GCHandleType.Pinned);

				fullcommand = "Command Line: " + fullcommand + "\n";
				gsIOUpdateMain(fullcommand, fullcommand.Length);
				code = ghostapi.gsapi_init_with_args(gsInstance, num_params, argPtrsStable.AddrOfPinnedObject());
				if (code < 0 && code != gsConstants.E_QUIT)
				{
					throw new GhostscriptException("gsFileSync: gsapi_init_with_args error");
				}
			}
			catch (DllNotFoundException except)
			{
                gsErrorReport("Exception: " + except.Message);
				in_params.result = GS_Result_t.gsFAILED;
				cleanup = false;
			}
			catch (BadImageFormatException except)
			{
                gsErrorReport("Exception: " + except.Message);
				in_params.result = GS_Result_t.gsFAILED;
				cleanup = false;
			}
			catch (GhostscriptException except)
			{
                gsErrorReport("Exception: " + except.Message);
			}
			catch (Exception except)
			{
                gsErrorReport("Exception: " + except.Message);
			}
			finally
			{
				/* All the pinned items need to be freed so the GC can do its job */
				if (cleanup)
				{
					for (int k = 0; k < num_params; k++)
					{
						argParam[k].Free();
					}
					argPtrsStable.Free();

					int code1 = ghostapi.gsapi_exit(gsInstance);
					if ((code == 0) || (code == gsConstants.E_QUIT))
						code = code1;

					ghostapi.gsapi_delete_instance(gsInstance);
					in_params.return_code = code;

					if ((code == 0) || (code == gsConstants.E_QUIT))
					{
						in_params.result = GS_Result_t.gsOK;
					}
					else
					{
						in_params.result = GS_Result_t.gsFAILED;
					}
					gsInstance = IntPtr.Zero;
				}
			}
			return in_params;
		}

		/* Process command line with gsapi_init_with_args */
		private void gsFileAsync(object data)
		{
			List<object> genericlist = data as List<object>;
			gsParamState_t Params = (gsParamState_t)genericlist[0];
			gsParamState_t Result = Params;
			int num_params = Params.args.Count;
			var argParam = new GCHandle[num_params];
			var argPtrs = new IntPtr[num_params];
			List<byte[]> CharacterArray = new List<byte[]>(num_params);
			GCHandle argPtrsStable = new GCHandle();
			int code = 0;
			bool cleanup = true;

			try
			{
				code = ghostapi.gsapi_new_instance(out gsInstance, IntPtr.Zero);
				if (code < 0)
				{
					throw new GhostscriptException("gsFileAsync: gsapi_new_instance error");
				}
				code = ghostapi.gsapi_set_stdio(gsInstance, stdin_callback, stdout_callback, stderr_callback);
				if (code < 0)
				{
					throw new GhostscriptException("gsFileAsync: gsapi_set_stdio error");
				}
				code = ghostapi.gsapi_set_arg_encoding(gsInstance, (int)gsEncoding.GS_ARG_ENCODING_UTF8);
				if (code < 0)
				{
					throw new GhostscriptException("gsFileAsync: gsapi_set_arg_encoding error");
				}

				/* Now convert our Strings to char* and get pinned handles to these.
					* This keeps the c# GC from moving stuff around on us */
				String fullcommand = "";
				for (int k = 0; k < num_params; k++)
				{
					CharacterArray.Add(System.Text.Encoding.UTF8.GetBytes((Params.args[k]+"\0").ToCharArray()));
					argParam[k] = GCHandle.Alloc(CharacterArray[k], GCHandleType.Pinned);
					argPtrs[k] = argParam[k].AddrOfPinnedObject();
					fullcommand = fullcommand + " " + Params.args[k];
				}

				/* Also stick the array of pointers into memory that will not be GCd */
				argPtrsStable = GCHandle.Alloc(argPtrs, GCHandleType.Pinned);

				fullcommand = "Command Line: " + fullcommand + "\n";
				gsIOUpdateMain(fullcommand, fullcommand.Length);
				code = ghostapi.gsapi_init_with_args(gsInstance, num_params, argPtrsStable.AddrOfPinnedObject());
				if (code < 0)
				{
					throw new GhostscriptException("gsFileAsync: gsapi_init_with_args error");
				}
			}
			catch (DllNotFoundException except)
			{
                gsErrorReport("Exception: " + except.Message);
				Params.result = GS_Result_t.gsFAILED;
				cleanup = false;
				Result = Params;
			}
			catch (BadImageFormatException except)
			{
                gsErrorReport("Exception: " + except.Message);
				Params.result = GS_Result_t.gsFAILED;
				cleanup = false;
				Result = Params;
			}
			catch (GhostscriptException except)
			{
                gsErrorReport("Exception: " + except.Message);
			}
			catch (Exception except)
			{
                gsErrorReport("Exception: " + except.Message);
			}
			finally
			{ 
				if (cleanup)
				{
					/* All the pinned items need to be freed so the GC can do its job */
					for (int k = 0; k < num_params; k++)
					{
						argParam[k].Free();
					}
					argPtrsStable.Free();

					int code1 = ghostapi.gsapi_exit(gsInstance);
					if ((code == 0) || (code == gsConstants.E_QUIT))
						code = code1;

					ghostapi.gsapi_delete_instance(gsInstance);
					Params.return_code = code;

					if ((code == 0) || (code == gsConstants.E_QUIT))
					{
						Params.result = GS_Result_t.gsOK;
						Result = Params;
					}
					else
					{
						Params.result = GS_Result_t.gsFAILED;
						Result = Params;
					}
					gsInstance = IntPtr.Zero;
				}
			}

			/* Completed. */
			gsCompleted(Result);
			return;
		}

		/* Processing with gsapi_run_string for callback progress */
		private void gsBytesAsync(object data)
		{
			List<object> genericlist = data as List<object>;
			gsParamState_t Params = (gsParamState_t)genericlist[0];
			gsParamState_t Result = Params;
			int num_params = Params.args.Count;
			var argParam = new GCHandle[num_params];
			var argPtrs = new IntPtr[num_params];
			List<byte[]> CharacterArray = new List<byte[]>(num_params);
			GCHandle argPtrsStable = new GCHandle();
			Byte[] Buffer = new Byte[gsConstants.GS_READ_BUFFER];

			int code = 0;
			int exitcode = 0;
			var Feed = new GCHandle();
			var FeedPtr = new IntPtr();
			String[] strParams = new String[num_params];
			FileStream fs = null;
			bool cleanup = true;

			try
			{
				/* Open the file */
				fs = new FileStream(Params.inputfile, FileMode.Open);
				var len = (int)fs.Length;

				code = ghostapi.gsapi_new_instance(out gsInstance, IntPtr.Zero);
				if (code < 0)
				{
					throw new GhostscriptException("gsBytesAsync: gsapi_new_instance error");
				}
				code = ghostapi.gsapi_set_stdio(gsInstance, stdin_callback, stdout_callback, stderr_callback);
				if (code < 0)
				{
					throw new GhostscriptException("gsBytesAsync: gsapi_set_stdio error");
				}
				code = ghostapi.gsapi_set_arg_encoding(gsInstance, (int)gsEncoding.GS_ARG_ENCODING_UTF8);
				if (code < 0)
				{
					throw new GhostscriptException("gsBytesAsync: gsapi_set_arg_encoding error");
				}

				/* Now convert our Strings to char* and get pinned handles to these.
					* This keeps the c# GC from moving stuff around on us */
				String fullcommand = "";
				for (int k = 0; k < num_params; k++)
				{
					CharacterArray.Add(System.Text.Encoding.UTF8.GetBytes((Params.args[k]+"\0").ToCharArray()));
					argParam[k] = GCHandle.Alloc(CharacterArray[k], GCHandleType.Pinned);
					argPtrs[k] = argParam[k].AddrOfPinnedObject();
					fullcommand = fullcommand + " " + Params.args[k];
				}

				/* Also stick the array of pointers into memory that will not be GCd */
				argPtrsStable = GCHandle.Alloc(argPtrs, GCHandleType.Pinned);

				fullcommand = "Command Line: " + fullcommand + "\n";
				gsIOUpdateMain(fullcommand, fullcommand.Length);
				code = ghostapi.gsapi_init_with_args(gsInstance, num_params, argPtrsStable.AddrOfPinnedObject());
				if (code < 0)
				{
					throw new GhostscriptException("gsBytesAsync: gsapi_init_with_args error");
				}

				/* Pin data buffer */
				Feed = GCHandle.Alloc(Buffer, GCHandleType.Pinned);
				FeedPtr = Feed.AddrOfPinnedObject();

				/* Now start feeding the input piece meal and do a call back
				 * with our progress */
				if (code == 0)
				{
					int count;
					double perc;
					int total = 0;
					int ret_code;

					ret_code = ghostapi.gsapi_run_string_begin(gsInstance, 0, ref exitcode);
					if (exitcode < 0)
					{
						code = exitcode;
						throw new GhostscriptException("gsBytesAsync: gsapi_run_string_begin error");
					}

					while ((count = fs.Read(Buffer, 0, gsConstants.GS_READ_BUFFER)) > 0)
					{
						ret_code = ghostapi.gsapi_run_string_continue(gsInstance, FeedPtr, count, 0, ref exitcode);
						if (exitcode < 0)
						{
							code = exitcode;
							throw new GhostscriptException("gsBytesAsync: gsapi_run_string_continue error");
						}

						total = total + count;
						perc = 100.0 * (double)total / (double)len;
						gsProgressChanged(Params, (int)perc);
					}
					ret_code = ghostapi.gsapi_run_string_end(gsInstance, 0, ref exitcode);
					if (exitcode < 0)
					{
						code = exitcode;
						throw new GhostscriptException("gsBytesAsync: gsapi_run_string_end error");
					}
				}
			}
			catch (DllNotFoundException except)
			{
                gsErrorReport("Exception: " + except.Message);
				Params.result = GS_Result_t.gsFAILED;
				cleanup = false;
				Result = Params;
			}
			catch (BadImageFormatException except)
			{
                gsErrorReport("Exception: " + except.Message);
				Params.result = GS_Result_t.gsFAILED;
				cleanup = false;
				Result = Params;
			}
			catch (GhostscriptException except)
			{
                gsErrorReport("Exception: " + except.Message);
			}
			catch (Exception except)
			{
                /* Could be a file io issue */
                gsErrorReport("Exception: " + except.Message);
				Params.result = GS_Result_t.gsFAILED;
				cleanup = false;
				Result = Params;
			}
			finally
			{
				if (cleanup)
				{
					fs.Close();

					/* Free pinned items */
					for (int k = 0; k < num_params; k++)
					{
						argParam[k].Free();
					}
					argPtrsStable.Free();
					Feed.Free();

					/* gs clean up */
					int code1 = ghostapi.gsapi_exit(gsInstance);
					if ((code == 0) || (code == gsConstants.E_QUIT))
						code = code1;

					ghostapi.gsapi_delete_instance(gsInstance);
					Params.return_code = code;

					if ((code == 0) || (code == gsConstants.E_QUIT))
					{
						Params.result = GS_Result_t.gsOK;
						Result = Params;
					}
					else
					{
						Params.result = GS_Result_t.gsFAILED;
						Result = Params;
					}
					gsInstance = IntPtr.Zero;
				}
			}
			gsCompleted(Result);
			return;
		}

		/* Worker task for using display device */
		private void DisplayDeviceAsync(object data)
		{
			int code = 0;
			List<object> genericlist = data as List<object>;
			gsParamState_t gsparams = (gsParamState_t)genericlist[0];
			gsParamState_t Result = gsparams;
			GCHandle argPtrsStable = new GCHandle();
			int num_params = gsparams.args.Count;
			var argParam = new GCHandle[num_params];
			var argPtrs = new IntPtr[num_params];
			List<byte[]> CharacterArray = new List<byte[]>(num_params);
			bool cleanup = true;

			gsparams.result = GS_Result_t.gsOK;

			try
			{
				code = ghostapi.gsapi_new_instance(out dispInstance, IntPtr.Zero);
				if (code < 0)
				{
					throw new GhostscriptException("DisplayDeviceAsync: gsapi_new_instance error");
				}

				code = ghostapi.gsapi_set_stdio(dispInstance, stdin_callback, stdout_callback, stderr_callback);
				if (code < 0)
				{
					throw new GhostscriptException("DisplayDeviceAsync: gsapi_set_stdio error");
				}

				code = ghostapi.gsapi_set_arg_encoding(dispInstance, (int)gsEncoding.GS_ARG_ENCODING_UTF8);
				if (code < 0)
				{
					throw new GhostscriptException("DisplayDeviceAsync: gsapi_set_arg_encoding error");
				}

				code = ghostapi.gsapi_set_display_callback(dispInstance, ptr_display_struct);
				if (code < 0)
				{
					throw new GhostscriptException("DisplayDeviceAsync: gsapi_set_display_callback error");
				}

				String fullcommand = "";
				for (int k = 0; k < num_params; k++)
				{
					CharacterArray.Add(System.Text.Encoding.UTF8.GetBytes((gsparams.args[k] + "\0").ToCharArray()));
					argParam[k] = GCHandle.Alloc(CharacterArray[k], GCHandleType.Pinned);
					argPtrs[k] = argParam[k].AddrOfPinnedObject();
					fullcommand = fullcommand + " " + gsparams.args[k];
				}
				argPtrsStable = GCHandle.Alloc(argPtrs, GCHandleType.Pinned);

				fullcommand = "Command Line: " + fullcommand + "\n";
				gsIOUpdateMain(fullcommand, fullcommand.Length);
				code = ghostapi.gsapi_init_with_args(dispInstance, num_params, argPtrsStable.AddrOfPinnedObject());
				if (code < 0)
				{
					throw new GhostscriptException("DisplayDeviceAsync: gsapi_init_with_args error");
				}
			}

			catch (DllNotFoundException except)
			{
                gsErrorReport("Exception: " + except.Message);
				gsparams.result = GS_Result_t.gsFAILED;
				cleanup = false;
				Result = gsparams;
			}
			catch (BadImageFormatException except)
			{
                gsErrorReport("Exception: " + except.Message);
				gsparams.result = GS_Result_t.gsFAILED;
				cleanup = false;
				Result = gsparams;
			}
			catch (GhostscriptException except)
			{
                gsErrorReport("Exception: " + except.Message);
				gsparams.result = GS_Result_t.gsFAILED;
				if (dispInstance != IntPtr.Zero)
					ghostapi.gsapi_delete_instance(dispInstance);
				dispInstance = IntPtr.Zero;
			}
			catch (Exception except)
			{
                gsErrorReport("Exception: " + except.Message);
				gsparams.result = GS_Result_t.gsFAILED;
				if (dispInstance != IntPtr.Zero)
					ghostapi.gsapi_delete_instance(dispInstance);
				dispInstance = IntPtr.Zero;
			}
			finally
			{
				if (cleanup)
				{
					for (int k = 0; k < num_params; k++)
					{
						argParam[k].Free();
					}
					argPtrsStable.Free();
					Result = gsparams;

					if (gsparams.result == GS_Result_t.gsOK && (gsparams.task == GS_Task_t.DISPLAY_DEV_NON_PDF ||
						gsparams.task == GS_Task_t.DISPLAY_DEV_THUMBS_NON_PDF))
					{
						gsParamState_t result = DisplayDeviceClose();
						if (gsparams.result == 0)
						{
							gsparams.result = result.result;
						}
					}
				}
			}
			gsCompleted(Result);
			return;
		}

		/* Call the appropriate worker thread based upon the task
		 * that we have to do */
		private gsStatus RunGhostscriptAsync(gsParamState_t Params)
		{
            try
			{
				if (m_worker_busy)
                { 
                    return gsStatus.GS_BUSY;
				}

				switch (Params.task)
				{
					case GS_Task_t.PS_DISTILL:
						m_worker = new Thread(gsBytesAsync);
						break;
					case GS_Task_t.DISPLAY_DEV_NON_PDF:
					case GS_Task_t.DISPLAY_DEV_PDF:
					case GS_Task_t.DISPLAY_DEV_THUMBS_NON_PDF:
					case GS_Task_t.DISPLAY_DEV_THUMBS_PDF:
						m_worker = new Thread(DisplayDeviceAsync);
						break;
					case GS_Task_t.SAVE_RESULT:
					case GS_Task_t.CREATE_XPS:
					default:
						m_worker = new Thread(gsFileAsync);
						break;
				}

				var arguments = new List<object>();
				arguments.Add(Params);
				arguments.Add(this);
                m_worker_busy = true;
                m_worker.Start(arguments);

				return gsStatus.GS_READY;
			}
			catch (OutOfMemoryException)
			{
				Console.WriteLine("Memory allocation failed during gs rendering\n");
				return gsStatus.GS_ERROR;
			}
		}

#region public_methods

		/* Direct call on gsapi to get the version of the DLL we are using */
		public String GetVersion()
		{
			gsapi_revision_t vers;
			vers.copyright = IntPtr.Zero;
			vers.product = IntPtr.Zero;
			vers.revision = 0;
			vers.revisiondate = 0;
			int size = System.Runtime.InteropServices.Marshal.SizeOf(vers);

			try
			{
				if (ghostapi.gsapi_revision(ref vers, size) == 0)
				{
					String product = Marshal.PtrToStringAnsi(vers.product);
					String output;
					int major = vers.revision / 100;
					int minor = vers.revision - major * 100;
					String versnum = major + "." + minor;
					output = product + " " + versnum;
					return output;
				}
				else
					return null;
			}
			catch (Exception except)
			{
                gsErrorReport("Exception: " + except.Message);
			}
			return null;
		}

		/* Use syncronous call to ghostscript to get the
		 * number of pages in a PDF file */
		public int GetPageCount(String fileName)
		{
			gsParamState_t gsparams = new gsParamState_t();
			gsParamState_t result;
			gsparams.args = new List<string>();

			gsparams.args.Add("gs");
			gsparams.args.Add("-dNODISPLAY");
			gsparams.args.Add("-dNOPAUSE");
			gsparams.args.Add("-dBATCH");
			gsparams.args.Add("-I%rom%Resource/Init/");
			//gsparams.args.Add("-q");
			gsparams.args.Add("-sFile=\"" + fileName + "\"");
			gsparams.args.Add("--permit-file-read=\"" + fileName + "\"");
			gsparams.args.Add("-c");
			gsparams.args.Add("\"File (r) file runpdfbegin pdfpagecount = quit\"");
			gsparams.task = GS_Task_t.GET_PAGE_COUNT;
			m_params = gsparams;

			result = gsFileSync(gsparams);

			if (result.result == GS_Result_t.gsOK)
				return m_params.num_pages;
			else
				return -1;
		}

		/* Launch a thread rendering all the pages with the display device
		 * to distill an input PS file and save as a PDF. */
		public gsStatus DistillPS(String fileName, int resolution)
		{
			gsParamState_t gsparams = new gsParamState_t();
			gsparams.args = new List<string>();

			gsparams.inputfile = fileName;
			gsparams.args.Add("gs");
			gsparams.args.Add("-dNOPAUSE");
			gsparams.args.Add("-dBATCH");
			gsparams.args.Add("-I%rom%Resource/Init/");
			gsparams.args.Add("-dSAFER");
			gsparams.args.Add("-sDEVICE=pdfwrite");
            gsparams.outputfile = Path.GetTempFileName();
            gsparams.args.Add("-o" + gsparams.outputfile);
			gsparams.task = GS_Task_t.PS_DISTILL;

			return RunGhostscriptAsync(gsparams);
		}

		/* Launch a thread rendering all the pages with the display device
		 * to collect thumbnail images or full resolution.   */
		public gsStatus gsDisplayDeviceRenderAll(String fileName, double zoom, bool aa, GS_Task_t task)
		{
			gsParamState_t gsparams = new gsParamState_t();
			int format = (gsConstants.DISPLAY_COLORS_RGB |
							gsConstants.DISPLAY_DEPTH_8 |
							gsConstants.DISPLAY_BIGENDIAN);
			int resolution = (int)(72.0 * zoom + 0.5);

			gsparams.args = new List<string>();
			gsparams.args.Add("gs");
			gsparams.args.Add("-dNOPAUSE");
			gsparams.args.Add("-dBATCH");
			gsparams.args.Add("-I%rom%Resource/Init/");
			gsparams.args.Add("-dSAFER");
			gsparams.args.Add("-r" + resolution);
			if (aa)
			{
				gsparams.args.Add("-dTextAlphaBits=4");
				gsparams.args.Add("-dGraphicsAlphaBits=4");
			}
			gsparams.args.Add("-sDEVICE=display");
			gsparams.args.Add("-dDisplayFormat=" + format);
			gsparams.args.Add("-f");
			gsparams.args.Add(fileName);
			gsparams.task = task;
			gsparams.currpage = 0;
            m_params.currpage = 0;
            return RunGhostscriptAsync(gsparams);
		}


		/* Launch a thread rendering a set of pages with the display device.  For use with languages
		   that can be indexed via pages which include PDF and XPS */
		public gsStatus gsDisplayDeviceRenderPages(String fileName, int first_page, int last_page, double zoom)
		{
			gsParamState_t gsparams = new gsParamState_t();
			int format = (gsConstants.DISPLAY_COLORS_RGB |
							gsConstants.DISPLAY_DEPTH_8 |
							gsConstants.DISPLAY_LITTLEENDIAN);
			int resolution = (int)(72.0 * zoom + 0.5);

			gsparams.args = new List<string>();
			gsparams.args.Add("gs");
			gsparams.args.Add("-dNOPAUSE");
			gsparams.args.Add("-dBATCH");
			gsparams.args.Add("-I%rom%Resource/Init/");
			gsparams.args.Add("-dSAFER");
			gsparams.args.Add("-r" + resolution);
			gsparams.args.Add("-sDEVICE=display");
			gsparams.args.Add("-dDisplayFormat=" + format);
			gsparams.args.Add("-dFirstPage=" + first_page);
			gsparams.args.Add("-dLastPage=" + last_page);
			gsparams.args.Add("-f");
			gsparams.args.Add(fileName);
			gsparams.task = GS_Task_t.DISPLAY_DEV_PDF;
			gsparams.currpage = first_page - 1;
            m_params.currpage = first_page - 1;

            return RunGhostscriptAsync(gsparams);
		}

		/* Close the display device and delete the instance */
		public gsParamState_t DisplayDeviceClose()
		{
			int code = 0;
			gsParamState_t out_params = new gsParamState_t();

			out_params.result = GS_Result_t.gsOK;

			try
			{
				int code1 = ghostapi.gsapi_exit(dispInstance);
				if ((code == 0) || (code == gsConstants.E_QUIT))
					code = code1;

				ghostapi.gsapi_delete_instance(dispInstance);
				dispInstance = IntPtr.Zero;

			}
			catch (Exception except)
			{
                gsErrorReport("Exception: " + except.Message);
				out_params.result = GS_Result_t.gsFAILED;
			}

			return out_params;
		}

		/* Check if gs is currently busy */
		public gsStatus GetStatus()
		{
			if (m_worker_busy)
				return gsStatus.GS_BUSY;
			else
				return gsStatus.GS_READY;
		}
#endregion
	}
}